Laser initiated rocket type igniter



Jim 10, 1967 F. B. NIELSEN 3,296,795

LASER INITIATED ROCKET TYPE IGNITER Filed Aug. 4, 1964 INVENTOR. FLOYD 5 NIELSEN ATTORNEYS developed for the ignition of the rocket clusters.

ess may be either direct or indirect.

received through the casing wall at any point.

Utnted States Patent 3,296,795 LASERHINITIATED ROCKET TYPE IGNITER Floyd B.1Nielsen, San Jose, Calif., assignor to the United States of America as represented by the Secretary of the Air Force Filed Aug..4, 1964, Ser. No. 387,538 4 Claims. (Cl. 60--39.82)

The invention relates to a solid propellant igniter, and more particularly to, a device for igniting rockets, either singly or. in clusters, by beaming up the rocket nozzle a laseror other electromagnetic beam, focused on a primer.

In successful firing of a cluster of large segmented propellant: booster rockets, solid propellant rocket motors have been arranged in segmented quadrangle configuration, producing a high thrust in a very short space of time, measured in seconds.

The success of the project depends upon the techniques Simultaneoustignition of all cluster barrels is an absolute essential. If one of the motors should fail to ignite, or if all motorsmaking up the cluster should fail to ignite, or if all motors making up the cluster should fail to ignite simultaneously, the launching would also fail. The control steering system would be unable to compensate for course changesucaused by late firing or failure in firing of a single barrel.

Hypergolic ignition systems have been used. In this type of system, a highly reactive hypergolic fluid is sprayed along the solid. grain of each barrel of the cluster for instant initiation of combustion. In this type of ignition a complicated and very. sensitive manifold and valve system is necessaryto control the flow of hypergolic fluid to all barrels.

tricalcircuitry and hardware attached internally of the rocket casing. High pressure seals are necessary for lead ins; and other devices involved.

\ p The object of the present invention is the provision of a new ignition system, applicable both for single or clustered booster rockets, and capable of simultaneous ignition of segmented solid propellant rockets whose capability is of the order of multi-million pound thrust.

A further objectof the invention is the provision of a laser initiated ignition system for rockets, singly or in clusters; wherein sensitive valve systems, wiring, wiring seals and other contact devices heretofore necessary are eliminated.

In the present invention a device is provided which makes possible the utilization of a pulse of high energy, beamed from a laser for igniting solid propellant rockets.

In the device of the present invention, the ignition proc- The laser beam may trigger: the rocket motor directly, or it may be used to ignite a small. igniter rocket motor, the exhaust flame of Whichlcornes in contact with the solid propellant of the primary rocket motor and causes it to ignite. In either case, there is no physicalcontact with the primary rocket or.with the starter rocket. The ignition impulse is not Instead, the igniter receives its impulse through the nozzle.

In conventional electrical ignition systems, contact must be arranged for in a hazardous and sensitive area. There is extreme danger of accidental firing. In the laser system protection from misfiring can be provided by shades, mirrors; optical blocking or. other safety equipment, removed before firing. The.1asers high energy pulse is beamed directly,.or by reflectors up the nozzle of the booster and focused with a high-resolution optical lens on the igniter motors indicator, which is the equivalent of a firing pin. Ignition of a cluster of rockets can be performed simultaneously by splitting a laser beam optically, or by a set of laser beams triggered and powered by a single power source.

A further object of the invention is, therefore, the provision of a lens focusing device adaptable for use with and in combination with booster rocket motors, or starter rocket motors whereby a beam of electromagnetic energy is focused to initiate an igniter train and ignite the solid propellant grain of a rocket motor.

In the drawing:

FIG. 1 is a cross sectional view of the laser initiator train, and

FIG. 2 is a cross sectional view of the laser train, showing its attachment to the casing containing the solid propellant grain to be ignited.

Referring more in detail to the drawing:

Solid propellant grain 10 is housed in a casing 12, which has a front closure 14 and nozzles 15. These nozzles as shown are igniter nozzles for a solid propellant motor, and are adapted to be arranged for ignition of a single motor, or a cluster.

The initiator train unit is designated generally by the numeral 16. It is secured to a neck 18 provided therefor in the casing 12 by means of a uniting element 20. The element 20 is threadedly or otherwise suitably secured to a bore in the neck 18, and to internal threads on a casing 22 of the initiator unit 16. A basket 24 is also secured to a counter bore in the neck element 18, and contains pellets 26 of initiator material, being capable, when ignited, of igniting the propellant grain 10.

The element 20 is provided with a central recess which contains initiator material 28, such as boron potassium nitrate in granular form and is separated from the pellet material in the basket by an aluminum foil burst diaphragm 29. Hot gases produced by the burning granules rupture and burst the diaphragm to ignite the pellets 26. A counter bore in the element 20 provides space for a heat sensitive primer 30 held in place by a ring 32 of inert material, and a window 34.

A lens holder 36 is secured to the casing 22, by threaded or other adjustable connection, for providing adjustment of the position of the lens unit 38 which is mounted in the lens holder 36.

The lens unit 38, as shown, comprises a pair of concentrating lenses 40.

The lenses 40 are capable of receiving and concentrating a laser beam 42 or a beam of some other form of electromagnetic energ and when they are focused upon the primer 30, the primer will ignite. The train of ignition follows through the granular material 28, through the pellets 26, igniting the solid fuel 10, which, in turn, is directed to a solid propellant motor through a concentrating lens, one of which is shown at 15.

I claim:

1. A laser initiated rocket-type igniter comprising a casing for the containment of a solid fuel, a neck element on said casing providing an opening, a perforated basket for containing initiator pellets secured to said neck and internally of said casing, said initiator pellets being capable, when ignited, of igniting said initiator pellets, a heat lens, a lens focusing assembly, an initiator train, said train comprising initiator material in granular form, capable, when ignited, of igniting said initiator pellets, a heat sensitive primer located at the focal point of said lens, said lens being capable of focusing an electromagnetic beam upon said heat sensitive primer, whereby ignition follows through the whole train to the said pellets and to said solid fuel.

2. A laser initiated rocket-type igniter comprising a casing for the containment of a solid fuel, a perforated basket located adjacent one end of said casing and internally thereof, initiator pellets in said basket capable, when themselves ignited, to ignite said solid fuel, an initiator train for causing the ignition of said initiator pellets, said train comprising an element for the containment of initiator granules, and a heat sensitive primer, a lens system, adjusting means for focusing said lens system upon said heat sensitive primer, said lens system capable of receiving an electromagnetic beam collecting said beam and focusing it upon said heat sensitive primer, whereby ignition is caused to travel through said train from said primer to said granular material to said initiator pellets to said solid fuel.

3. A laser initiated rocket-type rocket igniter comprising, a casing forthe containment of solid fuel, nozzles on said casing for the transfer of hot jets from said casing to a primary motor, means for igniting said solid fuel in said casing, said means comprising, an electromagnetic beam, a heat sensitive primer, a lens system, a lens holder adjustable for focusing said lens on said primer, an igniter train for transmitting ignition from said primer to said solid fuel, said igniter train comprising, igniter material in pellet form, positioned within said casing, a uniting element uniting said lens holder to said casing in an area adjacent said igniter material, igniter material in granular form contained within said uniting element, said granular material positioned between said pellets and said primer, whereby ignition initiated by said electromagnetic beam 4 travels through said granular material and said pellets to ignite said solid fuel in said casing.

4. A device for igniting solid propellant rocket fuel, said device comprising a casing for the containment of solid fuel, a lens system including a lens and a lens holder, capable of collecting and focusing laser beams, a uniting element uniting said casing and said lens holder, an initiator train carried within said uniting element and comprising a primer located, when operative, at the focal point of said lens, said initiator train comprising initiator material located between said primer and said sold fuel, said initiator material being of graded sizes from granular to pellets, a perforated basket located internally of said casing for containing said pellet and granular material, and a burst diaphragm located between said pellet and said granular material whereby ignition is explosively transmitted from said granular material to said pellets.

References Cited by the Examiner UNITED STATES PATENTS 2,561,670 7/1951 Miller et al 10249 2,685,837 8/1954 Sage et a1 10249 2,995,088 8/1961 Asplund 102-70 3,003,419 10/1961 Fite --39.82 3,177,651 4/1965 Lawrence 6039.82 3,217,088 11/1965 Steierman 331-94.5

MARK NEWMAN, Primary Examiner. D. HART, Assistant Examiner. 

1. A LASER INITIATED ROCKET-TYPE IGNITER COMPRISING A CASING FOR THE CONTAINMENT OF A SOLID FUEL, A NECK ELEMENT ON SAID CASING PROVIDING AN OPENING, A PERFORATED BASKET FOR CONTAINING INITIATOR PELLETS SECURED TO SAID NECK AND INTERNALLY OF SAID CASING, SAID INITIATOR PELLETS BEING CAPABLE, WHEN IGNITED, OF IGNITING SAID INITIATOR PELLETS, A HEAT LENS, A LENS FOCUSING ASSEMBLY, AN INITIATOR TRAIN, SAID TRAIN COMPRISING INITIATOR MATERIAL IN GRANULAR FORM, CAPABLE, WHEN IGNITED, OF IGNITING SAID INITIATOR PELLETS, A HEAT SENSITIVE PRIMER LOCATED AT THE FOCAL POINT OF SAID LENS, SAID LENS BEING CAPABLE OF FOCUSING AN ELECTROMAGNETIC BEAM UPON SAID HEAT SENSITIVE PRIMER, WHEREBY IGNITION FOLLOWS THROUGH THE WHOLE TRAIN TO THE SAID PELLETS AND TO SAID SOLID FUEL. 